
:root {
    --primary: #409eff;
    --sidebar-bg: #eaf6fb;
    --content-bg: #f8fbfd;
    --header-bg: #f4fafc;
    --table-header: #f5f5f5;
    --border: #eee;
    --btn-info: #409eff;
    --btn-danger: #f56c6c;
    --btn-warning: #f6c23e;
}
* { box-sizing: border-box; }
body {
    margin: 0;
    font-family: 'Segoe UI', 'Arial', 'Microsoft YaHei', sans-serif;
    background: var(--content-bg);
    color: #333;
}
.layout {
    display: flex;
    min-height: 100vh;
}
.sidebar {
    width: 220px;
    background: var(--sidebar-bg);
    padding-top: 0;
    display: flex;
    flex-direction: column;
    align-items: stretch;
}
.sidebar-title {
    height: 64px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 20px;
    font-weight: bold;
    letter-spacing: 2px;
    background: var(--header-bg);
    border-bottom: 1px solid var(--border);
}
.sidebar-menu {
    flex: 1;
    padding: 20px 0 0 0;
}
.sidebar-menu a {
    display: flex;
    align-items: center;
    padding: 14px 32px;
    color: #333;
    text-decoration: none;
    font-size: 16px;
    border-left: 4px solid transparent;
    transition: background 0.2s, border-color 0.2s;
}
.sidebar-menu a.active,
.sidebar-menu a:hover {
    background: #fff;
    border-left: 4px solid var(--primary);
    color: var(--primary);
    font-weight: bold;
}
.sidebar-logout {
    margin: 0 24px 24px 24px;
    padding: 10px 0;
    text-align: center;
    background: #fff;
    border-radius: 6px;
    cursor: pointer;
    color: #888;
    font-size: 16px;
    border: 1px solid var(--border);
    transition: color 0.2s, border 0.2s;
}
.sidebar-logout:hover {
    color: #f56c6c;
    border: 1px solid #f56c6c;
}
.main {
    flex: 1;
    display: flex;
    flex-direction: column;
    background: var(--content-bg);
}
.header {
    height: 64px;
    background: var(--header-bg);
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0 40px 0 24px;
    border-bottom: 1px solid var(--border);
    position: relative;
}
.header-title {
    font-size: 20px;
    font-weight: bold;
    letter-spacing: 2px;
    color: #4682b4;
}
.header-user {
    font-size: 16px;
    color: #666;
}
.content {
    flex: 1;
    padding: 32px 32px 0 32px;
    position: relative;
}
/* 背景装饰 */
.decoration-yellow, .decoration-red, .decoration-green {
    position: absolute;
    opacity: 0.18;
    z-index: 0;
    pointer-events: none;
}
.decoration-yellow {
    top: -24px; right: 60px;
    width: 350px; height: 120px;
    background: #ffe082;
    border-radius: 70px 180px 80px 120px;
    transform: rotate(15deg);
}
.decoration-red {
    left: 120px; top: 320px;
    width: 120px; height: 120px;
    background: #f44336;
    clip-path: polygon(50% 0%, 0% 100%, 100% 100%);
    border-radius: 16px;
}
.decoration-green {
    right: 0; bottom: 0;
    width: 340px; height: 240px;
    background: #4caf50;
    border-radius: 60px 80px 190px 140px;
    transform: rotate(-20deg);
}
/* 表格样式 */
.card {
    margin: 0 auto;
    background: #fff;
    border-radius: 10px;
    box-shadow: 0 0 12px rgba(180,200,220,0.08);
    padding: 28px 24px 24px 24px;
    position: relative;
    z-index: 1;
    max-width: 100%;
    overflow-x: auto;
}
.actions-bar {
    display: flex;
    align-items: center;
    margin-bottom: 14px;
    gap: 12px;
}
.search-input {
    padding: 8px 12px;
    border: 1px solid #ddd;
    border-radius: 5px;
    font-size: 15px;
    outline: none;
    margin-right: 8px;
    background: #fafbfc;
}
.btn {
    padding: 6px 16px;
    border: none;
    border-radius: 5px;
    font-size: 15px;
    cursor: pointer;
    margin: 0 2px;
    transition: background 0.2s;
}
.btn-info { background: var(--btn-info); color: #fff; }
.btn-danger { background: var(--btn-danger); color: #fff; }
.btn-warning { background: var(--btn-warning); color: #fff; }
.btn-info:hover { background: #2476d1; }
.btn-danger:hover { background: #d94444; }
.btn-warning:hover { background: #d39e09; }
.table {
    width: 100%;
    border-collapse: collapse;
    margin-bottom: 0;
    background: #fff;
}
.table th,
.table td {
    padding: 12px 10px;
    text-align: left;
    border-bottom: 1px solid var(--border);
    font-size: 15px;
}
.table th {
    background: var(--table-header);
    font-weight: bold;
    color: #666;
}
.table tr:last-child td {
    border-bottom: none;
}
/* 卡片课程 */
.course-list {
    display: flex;
    flex-wrap: wrap;
    gap: 24px;
    margin-top: 16px;
    z-index: 1;
    position: relative;
}
.course-card {
    width: 280px;
    background: #fff;
    border-radius: 12px;
    box-shadow: 0 1px 6px rgba(50,120,180,0.09);
    display: flex;
    flex-direction: column;
    overflow: hidden;
    transition: box-shadow 0.2s;
}
.course-card:hover {
    box-shadow: 0 6px 18px rgba(60,120,180,0.18);
}
.course-image {
    width: 100%;
    height: 160px;
    object-fit: cover;
    background: #f5f5f5;
}
.course-info {
    padding: 14px 15px 10px 15px;
    flex: 1;
    display: flex;
    flex-direction: column;
    gap: 8px;
}
.course-title {
    font-weight: bold;
    font-size: 18px;
    margin-bottom: 4px;
    color: #333;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}
.course-desc {
    font-size: 14px;
    color: #555;
    line-height: 1.4em;
    height: 2.8em;
    overflow: hidden;
    text-overflow: ellipsis;
}
.course-small {
    font-size: 13px;
    color: #999;
}
/* 响应式 */
@media (max-width: 900px) {
    .layout { flex-direction: column; }
    .sidebar { width: 100%; flex-direction: row; height: 56px; }
    .sidebar-title { display: none; }
    .sidebar-menu { display: flex; flex-direction: row; padding: 0 8px; }
    .sidebar-menu a { padding: 10px 18px; border-left: none; border-bottom: 2px solid transparent; }
    .sidebar-menu a.active, .sidebar-menu a:hover { border-bottom: 2px solid var(--primary); }
    .sidebar-logout { margin: 0 10px; }
    .main { padding-top: 0; }
    .content { padding: 16px 4vw 0 4vw; }
    .decoration-yellow, .decoration-red, .decoration-green { display: none; }
}
